A fixing device for use in an electrophotographic image forming apparatus is known in the art, which includes a tubular fusing film, a heating element disposed inside the tubular fusing film, a thick pressure pad disposed on an inner surface of the fusing film in such a manner that permits the fusing film to slide along the nip plate, and a pressure roller configured such that the fusing film is nipped between the pressure roller and the pressure pad. In this fixing device, the pressure pad has a hollow formed at a surface thereof in slidably contact with the fusing film, and a lubricant is held in this hollow to reduce friction between the pressure pad and the fusing film so that the fusing film is rotated smoothly.
In the fixing device as mentioned above, however, the pressure pad should be thick and thus have a great heat capacity such that the application of heat through the pressure pad to the fusing film (to be more specific, to a nip portion between the fusing film and the pressure roller) cannot be effected swiftly as desired. Moreover, the great capacity of heat of the pressure pad would retard the warm-up of lubricant and keep its viscosity at an undesirably high level during startup of the fixing device particularly under low-temperature conditions for example during wintertime or in cold climate areas; therefore, the friction between the fusing film and the pressure pad during startup of the fixing device would be so high that a desired level of smooth operation could not be performed at the worst.
There is a need to provide a fixing device in which lubricant can be heated quickly and its operation at startup can be performed smoothly.